Fault detection, isolation and recovery (FDIR) has generally been the responsibility of the ground system in the overall spacecraft control/command arrangement. Problems encountered with sensor, components or subsystems on the spacecraft had to be addressed and resolved from the ground. In such an arrangement, ground architectures support the dynamic upload of the resolution to complex spacecraft. This has been a continuing problem, since the number of monitor points and control points in the modern complex spacecraft systems exceeds 32,000, which represents a task which is close to impossible when the FDIR is completely based on the ground system.
In order to reduce the cost and complexity of operations, there is a need for FDIR to be resolved, whether completely or partially on-board of a spacecraft and ideally in a scalable hierarchical fashion.
Planning and scheduling of “activities” is another area of the spacecraft control/command where the complexity of operations makes it advantageous to move at least partially to on-board systems. Planning and scheduling are resource intensive processes both in terms of manpower and hardware. Each scheduling may take an extensive period of time to finalize and convert into command loads for uplink from ground to spacecraft.
Therefore the ability of an autonomous on-board checkout of the spacecraft and on-board planning and re-planning is a desirable feature of spacecraft operations to provide an operational capability of the spacecraft in the fraction of the time allotted for FDIR in present systems and reduces operation costs and flying the spacecraft with a minimum flight crew.